Construction Studies Theory – Higher Level(300 marks)

Time: 3 Hours

(a) Answer Question 1 and four other questions. (b) All questions carry equal marks. (c) Answers must be written in ink. (d) Drawings and sketches to be made in pencil. (e) Write the number of the question distinctly before each answer. (f) Neat freehand sketches to illustrate written descriptions should be made. (g) The name, sizes, dimensions and other necessary particulars of each material indicated must be noted on the drawings.

*P30*Pre-Leaving Certificate Examination, 2020Triailscrúdú na hArdteistiméireachta, 2020

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1. A dwelling house has an open-plan kitchen and dining area on the ground floor, as shown. The kitchen has a solid concrete floor with a 20 mm tile finish. The adjoining dining area has a suspended timber floor with a 20 mm tongue and groove hardwood finish on 200 mm × 40 mm joists. Both floors are highly insulated. The external wall of the house is a 400 mm concrete block wall with a full-fill insulated cavity.

(a) To a scale of 1:10, draw a vertical section through the external wall of the kitchen and through both the concrete and timber floors. Show the typical construction details from the bottom of the strip foundation to a level 400 mm above the finished floor and include the abutment of both floors. Show a width of 1.5 metres for each floor.

Note: It is not necessary to show the kitchen cabinets or the furniture.

(b) On your drawing, show the typical design detailing for the cross ventilation of the suspended timber floor through the solid concrete floor.

2. The main entrances of many older buildings were often not suitable for wheelchair users.

(a) Discuss in detail, using notes and freehand sketches, three design features of the main entrance of a modern dwelling house that make it suitable for all users. Indicate typical dimensions on your sketches.

(b) The accompanying drawing shows the layout of a bedroom and an adjoining bathroom, which is 2.3 m × 2.9 m. The location of the hot press is included in the sketch.

Using notes and freehand sketches, show a preferred layout for the bathroom space to ensure that it is suitable for a person in a wheelchair.

Indicate in your design sketches the location of the following:

• window • shower area • toilet • wash hand basin • grab rails

Include three typical dimensions.

(c) Discuss your preferred location for the bathroom items listed at 2(b) above.

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3. The drawing shows the ground floor plan and the front elevation of a terraced cottage. Also shown is a portion of the rear garden. The walls of the cottage are of random rubble construction and are rendered. The rear wall A-A is south facing. To provide additional living space, and to enhance the health and wellbeing of the occupants, it has been decided to build a single-storey extension, not greater than 20.0 m2 in area, to the rear of the cottage.

(a) Discuss three considerations that should be taken into account in the design of the extension to ensure that the health and wellbeing of the occupants is enhanced by building the extension.

(b) Using notes and freehand sketches, show a proposed design layout for the extension and the necessary modifications to the existing layout of the cottage.

(c) Discuss how your proposed design meets each consideration discussed at 3(a) above.

4. To meet the nearly Zero Energy Building (nZEB) requirements, many newly built houses use an air to water heat exchanger to provide heat for an underfloor heating system.

(a) Discuss in detail three advantages of this heating system over a traditional oil fired radiator system.

(b) A wood-burning stove, combined with a solar collector, provide central heating and hot water for a two-storey house. Using notes and a single-line diagram, show a typical design layout for both the central heating and the hot water systems. Show two independently controlled heating zones, one on each floor. Include three radiators on each floor and give the typical sizes of the pipework.

(c) Using notes and freehand sketches, describe two features that ensure that the system operates safely at all times. Discuss the importance of each safety feature outlined.

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5. The external wall of a house of timber frame construction has the following specification:

External render thickness 18 mm Concrete block outer leaf thickness 100 mm Cavity width 40 mm Oriented Strand Board (OSB) sheeting thickness 18 mm Timber stud inner leaf thickness 150 mm Mineral wool insulation between studs thickness 150 mm Plasterboard thickness 12.5 mm

Thermal data of outer leaf and cavity:

Resistance of the external surface (R) 0.048 m2 °C/W Resistivity of the external plaster (r) 2.170 m °C/W Conductivity of concrete block (k) 1.320 W/m °C Resistance of the cavity (R) 0.170 m2 °C/W Thermal data of inner leaf:

Conductivity of OSB sheeting (k) 0.130 W/m °C Conductivity of mineral wool (k) 0.040 W/m °C Conductivity of plasterboard (k) 0.160 W/m °C Resistance of the internal surface (R) 0.104 m2 °C/W

Note: The timber studs of the inner leaf need not be considered in your calculations.

(a) Calculate the U-value of the above external wall.

(b) Using the U-value of the wall obtained at 5(a) above and the following data, calculate the cost of heat lost annually through this wall:

• area of external wall 135 m2

• average internal temperature 22 °C• average external temperature 4 °C• heating period 10 hours daily for 43 weeks per annum • cost of oil 99 cent per litre• calorific value of oil 37350 kJ per litre• 1000 Watts 1 kJ per second.

(c) It is proposed to upgrade the thermal properties of the above wall to meet the Passive House standard by fixing expanded polystyrene to the external surface. Given the thermal conductivity (k) of expanded polystyrene as 0.037 W/m °C, calculate the thickness of expanded polystyrene required to achieve a U-value of 0.15 W/m2 °C.

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6. A middle-aged couple have decided to move to a smaller home in the countryside. They have obtained planning permission to build an eco-friendly home as shown. The couple are interested in house construction and wish to self-build their house with the help of work colleagues, family and friends. They have also engaged professional design supervision and an electrician. The house is of timber frame construction throughout, with an external rain screen of native larch.

(a) Discuss three advantages and three disadvantages of self-build as a method of building a house.

(b) Discuss in detail, using notes and freehand sketches, three features of the design shown that make the house suitable as a self-build project.

(c) Show, using notes and freehand sketches, two design features in the existing design that reduce the environmental impact of the house and help meet the nearly Zero Energy Building (nZEB) requirements. Justify your design choices.

7. The slated roof of a new house is constructed using prefabricated trussed rafters and has a pitch of 45 degrees. The internal span of the house is 4.0 metres. The roof is supported on external walls of timber frame construction, having a rendered concrete block external leaf.

Both the roof and the walls are highly insulated.

(a) To a scale of 1:10, draw a vertical section through the roof structure. Show the typical construction details from a level 400 mm below the ceiling up to ridge level, and include both external walls.

Show the typical design detailing at one of the eaves and include battens, membranes and four courses of slate at eaves. Label the components.

(b) On your drawing, show the typical dimensions of four roof members.

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8. (a) Discuss in detail, using notes and freehand sketches, two functional requirements of a foundation suitable for a dwelling house.

(b) A trial hole, as shown in the sketch, indicates a moderately firm clay subsoil for the foundations of a dwelling house. The external wall of the house is a 400 mm solid concrete block wall with a full-fill insulated cavity.

Consideration is being given at the design stage to using either:

• a traditional strip foundation or • a raft foundation.

Show, using notes and annotated freehand sketches, the typical design detailing for each type of foundation.

Recommend a preferred foundation for the house and give two reasons for your recommendation.

(c) Discuss in detail, three best practice guidelines that should be observed to ensure the maximum strength of concrete in a foundation.

9. It is proposed to design the external envelope of a dwelling house to be thermal bridge free. The drawing shows an outline section through a two-storey house having a 450 mm external concrete block wall with a 250 mm full-fill insulated cavity. The roof is a traditional cut roof, the first floor has tongue-and-groove flooring on timber joists and the ground floor is an insulated solid concrete floor.

(a) Select any three locations from those circled on the drawing and, using notes and freehand sketches, show best practice design detailing that will prevent the formation of a thermal bridge at each location selected.

(b) Discuss the importance of designing a building envelope that is thermal bridge free.

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10. (a) Using notes and freehand sketches, discuss the importance of any two of the following in Passive House design:

• space heating energy demand • building form • thermal bridging.

(b) The Passive House shown overheats in summer. Discuss two reasons why overheating occurs and, using notes and freehand sketches, show two design details for the house that would reduce the possibility of overheating.

(c) Discuss two advantages and two disadvantages of making the Passive House standard a planning requirement for all new housing in Ireland.

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10. Green design is about being green, rather than simply appearing to be green. So greening your house is about more than just buying all sorts of expensive ‘eco-bling’ and adding it to your house. Ironically, that could be just another display of consumerism. Rather, greening your house is about making responsible environmental choices based on what you want to do, what you can do and what you can afford. This means that - before we get into the minutiae of sustainable building materials - we should address some fundamentals, chief among which is the need to build modestly and source locally.

From: Contemporary Design Secrets: The Art of Building a House in the CountrysideJane Burnside (2013)

Discuss the above statement in detail and propose three best practice guidelines that would promote green, sustainable housing in Ireland.

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